JP7127556B2 - Ultrasonic probe and ultrasonic diagnostic equipment - Google Patents

Description

The present invention relates to an ultrasonic probe and an ultrasonic diagnostic apparatus.

Ultrasound diagnosis can be performed repeatedly because of its high safety and high safety. . An ultrasonic diagnostic apparatus used for performing such ultrasonic diagnosis is known. Ultrasound image data is obtained by transmitting ultrasonic waves to a subject from an ultrasonic probe having a piezoelectric element, receiving the reflected ultrasonic waves by the ultrasonic probe, and performing various processing on the received signals. is obtained by

In the ultrasonic probe, an electric field generated by the pyroelectric effect of the piezoelectric element may cause characteristic deterioration of the piezoelectric element. The pyroelectric effect is a phenomenon in which the polarization (surface charge) of a dielectric changes due to temperature changes. In general, the greater the piezoelectric characteristics of a material, the greater the pyroelectric coefficient. Therefore, when a material with high piezoelectric characteristics is used for a piezoelectric element, the amount of electric charge inevitably increases, and as a result, a large electric field is applied to the piezoelectric element. . Due to the influence of this electric field, a reverse electric field may be applied to the polarization direction of the piezoelectric element. If the electric field is large, that is, if the pyroelectric coefficient is large, the piezoelectric element may be depolarized. be. It is clear that the depolarization effect leads to deterioration of device characteristics.

For this reason, an ultrasonic probe is known in which a resistance (conductive paste) is applied between the metal electrodes of the piezoelectric element to constantly discharge the electric charge generated by heat, thereby preventing the application of voltage to the element due to the pyroelectric effect. (See Patent Document 1).

In addition, the signal line connected to the piezoelectric element (piezoelectric body) and the ground line are short-circuited by the control signal of the ultrasonic drive voltage when not driven, and the piezoelectric element is not operated in a high temperature environment when not in use or in an environment where the temperature changes rapidly. An ultrasonic probe that maintains reliability is known (see Patent Document 2).

JP-A-11-330578 Japanese Patent No. 6271127

However, in the ultrasonic probe of Patent Document 1, a resistor is always connected between the metal electrode on the signal line side and the metal electrode on the ground line side of the piezoelectric element. As a result, the characteristics of the piezoelectric element deteriorate due to the resistance.

Further, in the ultrasonic probe of Patent Document 2, the switch is switched depending on the presence or absence of the control signal for the ultrasonic drive voltage, and the signal line and the ground line are short-circuited/opened. Specifically, when there is a control signal for the ultrasonic driving voltage, the signal line and the ground line are open, and when there is no control signal for the ultrasonic driving voltage, the signal line and the ground line are short-circuited. For this reason, electrical control by a control signal for the ultrasonic drive voltage is required, which increases the cost.

SUMMARY OF THE INVENTION An object of the present invention is to easily eliminate deterioration of the characteristics of a piezoelectric element due to the pyroelectric effect.

In order to solve the above problems, the ultrasonic probe of the invention according to claim 1,
a piezoelectric element that transmits and receives ultrasonic waves to and from a subject;
an electric signal line electrically connected to a first electrode provided on the piezoelectric element, through which a drive signal input to the piezoelectric element and a reception signal output from the piezoelectric element flow;
a ground signal line provided with a gap from the electric signal line and electrically connected to a second electrode provided on the piezoelectric element;
a thermally deformable portion that deforms due to temperature and brings the electrical signal line and the ground signal line into contact at a temperature equal to or higher than a predetermined temperature.

The invention according to claim 2 is the ultrasonic probe according to claim 1,
The thermal deformation portion is made of a conductor and functions as part of at least one of the electric signal line and the ground signal line.

The invention according to claim 3 is the ultrasonic probe according to claim 1 or 2,
At least one of the electric signal line and the ground signal line has an insulator portion formed on a surface thereof.

The invention according to claim 4 is the ultrasonic probe according to claim 3,
The electrical signal line and the ground signal line are formed on the surface of the insulator,
a hollow portion that insulates the electric signal line and the ground signal line and contacts the electric signal line and the ground signal line due to deformation of the thermal deformation portion.

The invention according to claim 5 is the ultrasonic probe according to claim 3,
The insulator portion is arranged outside the electric signal line and the ground signal line, and the electric signal line or the ground signal line is formed on the surface on the piezoelectric element side.

The invention according to claim 6 is the ultrasonic probe according to any one of claims 1 to 5,
The thermally deformed portion is made of bimetal.

The invention according to claim 7 is the ultrasonic probe according to any one of claims 1 to 6,
The thermally deformable portion has a heat dissipation function.

The invention according to claim 8 is the ultrasonic probe according to any one of claims 1 to 7,
The electrical signal line, the ground signal line, and the thermal deformation portion are arranged in parallel.

The ultrasonic diagnostic apparatus of the invention according to claim 9,
The ultrasonic probe according to any one of claims 1 to 8,
a transmission unit that generates the drive signal and outputs it to the ultrasonic probe;
an image generation unit that generates ultrasound image data based on the received signal input from the ultrasound probe.

According to the present invention, it is possible to easily eliminate the characteristic deterioration of the piezoelectric element due to the pyroelectric effect.

1 is an external view of an ultrasonic diagnostic apparatus according to an embodiment of the present invention; FIG. 2 is a block diagram showing the functional configuration of an ultrasound diagnostic apparatus; FIG. 1 is a cross-sectional view of an ultrasonic probe according to an embodiment; FIG. (a) is a cross-sectional view showing a part of the ultrasonic probe before deformation of the embodiment. (b) is a cross-sectional view showing a part of the ultrasonic probe after deformation of the embodiment. (a) is a cross-sectional view showing a part of the ultrasonic probe before deformation of the first embodiment. (b) is a cross-sectional view showing a part of the ultrasonic probe after modification of the first embodiment. (a) is a cross-sectional view showing a part of the ultrasonic probe before deformation of the second embodiment. (b) is a cross-sectional view showing a part of the ultrasonic probe after modification of the second embodiment. (a) is a cross-sectional view showing a part of the ultrasonic probe before deformation of the third embodiment. (b) is a cross-sectional view showing a part of the ultrasonic probe after modification of the third embodiment. (a) is a cross-sectional view showing a part of the ultrasonic probe before deformation of the fourth embodiment. (b) is a cross-sectional view showing a part of the ultrasonic probe after modification of the fourth embodiment.

An embodiment and first to fourth examples according to the present invention will be described in detail in order with reference to the accompanying drawings. It should be noted that the present invention is not limited to the illustrated examples.

(Embodiment)
An embodiment according to the present invention will be described with reference to FIGS. 1 to 4. FIG. First, referring to FIG. 1, the overall configuration of an ultrasonic diagnostic apparatus 100 according to the present embodiment will be described. FIG. 1 is an external view of an ultrasonic diagnostic apparatus 100 according to this embodiment.

As shown in FIG. 1 , the ultrasonic diagnostic apparatus 100 includes an ultrasonic diagnostic apparatus body 1 and an ultrasonic probe 2 . The ultrasonic probe 2 transmits ultrasonic waves (transmitted ultrasonic waves) to the inside of a subject such as a living body (not shown), and the reflected waves of the ultrasonic waves reflected in the subject (reflected ultrasonic waves: echo) receive. The ultrasonic diagnostic apparatus main body 1 is connected to an ultrasonic probe 2 via a cable 3, and transmits an electric signal driving signal to the ultrasonic probe 2, thereby transmitting the ultrasonic probe 2 to the subject. Based on the received signal, which is an electric signal generated by the ultrasonic probe 2 in response to the reflected ultrasonic wave from the inside of the subject received by the ultrasonic probe 2, the ultrasonic wave is transmitted to the ultrasonic probe 2. The internal state inside the subject is imaged as ultrasound image data.

The ultrasonic probe 2 includes transducers 2a (see FIG. 2) made of piezoelectric elements, and the transducers 2a are arranged in a one-dimensional array in, for example, the azimuth direction (scanning direction). . In this embodiment, for example, an ultrasonic probe 2 having 192 transducers 2a is used. Note that the vibrators 2a may be arranged in a two-dimensional array. Also, the number of vibrators 2a can be set arbitrarily. In this embodiment, a linear electronic scan probe is used as the ultrasonic probe 2, and ultrasonic waves are scanned by a convex scanning method. can also be adopted. Communication between the ultrasonic diagnostic apparatus main body 1 and the ultrasonic probe 2 may be performed by wireless communication such as UWB (Ultra Wide Band) instead of wired communication via the cable 3 .

Next, with reference to FIG. 2, the functional configuration of the ultrasonic diagnostic apparatus 100 will be described. FIG. 2 is a block diagram showing the functional configuration of the ultrasonic diagnostic apparatus 100. As shown in FIG.

As shown in FIG. 2, the ultrasonic diagnostic apparatus main body 1 includes, for example, an operation input unit 11, a transmission unit 12, a reception unit 13, an image generation unit 14, an image processing unit 15, a DSC (Digital Scan Converter). ) 16 , a display unit 17 and a control unit 18 .

The operation input unit 11 receives operation input from an operator such as a doctor or a technician. The operation input unit 11 includes various switches for inputting various image parameters for displaying, for example, a command for instructing the start of diagnosis, data such as personal information of the subject, ultrasound image data, etc. on the display unit 17. , buttons, trackball, mouse, keyboard, etc., and outputs operation signals to the control unit 18 . The ultrasonic diagnostic apparatus main body 1 may be configured to include a touch panel provided on the display panel of the display unit 17 to receive touch input from the operator.

The transmission unit 12 is a circuit that supplies a drive signal, which is an electrical signal, to the ultrasound probe 2 via the cable 3 and causes the ultrasound probe 2 to generate transmission ultrasound under the control of the control unit 18 . . Also, the transmission unit 12 includes, for example, a clock generation circuit, a delay circuit, and a pulse generation circuit. The clock generation circuit is a circuit that generates a clock signal that determines the transmission timing and transmission frequency of the drive signal. The delay circuit sets a delay time for each individual path corresponding to each transducer 2a, delays the transmission of the drive signal by the set delay time, and performs the focusing of the transmission beam composed of the transmission ultrasonic waves. circuit. A pulse generation circuit is a circuit for generating a pulse signal as a drive signal at a predetermined cycle. The transmission unit 12 configured as described above drives, for example, a continuous part (eg, 64) of the plurality of (eg, 192) transducers 2a arranged in the ultrasound probe 2. to generate the transmitted ultrasound. Then, the transmission unit 12 performs scanning by shifting the transducer 2a to be driven in the azimuth direction (scanning direction) each time the transmission ultrasonic wave is generated.

The receiving unit 13 is a circuit that receives a reception signal, which is an electric signal, from the ultrasound probe 2 via the cable 3 under the control of the control unit 18 . The receiving unit 13 includes, for example, an amplifier, an A/D conversion circuit, and a phasing addition circuit. The amplifier is a circuit for amplifying the received signal with a preset amplification factor for each individual path corresponding to each transducer 2a. The A/D conversion circuit is a circuit for analog-to-digital conversion (A/D conversion) of the amplified received signal. The phasing addition circuit gives a delay time to each individual path corresponding to each transducer 2a to the A/D converted received signal to adjust the time phase, and adds them (phasing addition) to produce a sound. A circuit for generating line data.

Under the control of the control unit 18, the image generation unit 14 performs envelope detection processing and logarithmic compression on the sound ray data from the reception unit 13, adjusts the dynamic range and gain, and converts the luminance. , B (Brightness) mode image data consisting of pixels having luminance values as received energy can be generated. In other words, the B-mode image data represents the strength of the received signal by luminance. The image generation unit 14 generates B-mode image data as ultrasound image data whose image mode is B-mode, A (Amplitude) mode, M (Motion) mode, an image mode based on the Doppler method (color Doppler mode, etc.), and the like. It may also be possible to generate ultrasound image data in other image modes.

The image processing unit 15 performs image processing on the B-mode image data output from the image generation unit 14 according to various image parameters being set under the control of the control unit 18 . The image processing unit 15 also includes an image memory unit 15a configured by a semiconductor memory such as a DRAM (Dynamic Random Access Memory). The image processing unit 15 stores the image-processed B-mode image data in units of frames in the image memory unit 15a under the control of the control unit 18 . Image data in frame units is sometimes referred to as ultrasound image data or frame image data. The image processing unit 15 sequentially outputs the image data generated as described above to the DSC 16 under the control of the control unit 18 .

Under the control of the control unit 18 , the DSC 16 converts the image data received from the image processing unit 15 into an image signal for display, and outputs the image signal to the display unit 17 .

The display unit 17 can be a display device such as an LCD (Liquid Crystal Display), a CRT (Cathode-Ray Tube) display, an organic EL (Electronic Luminescence) display, an inorganic EL display, a plasma display, or the like. Under the control of the control unit 18 , the display unit 17 displays a still image or moving image of the ultrasonic image data on the display screen according to the image signal output from the DSC 16 . Also, the display unit 17 can adjust the dynamic range under the control of the control unit 18 .

The control unit 18 includes, for example, a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory). , controls the operation of each part of the ultrasonic diagnostic apparatus 100 according to the expanded program. The ROM is composed of a nonvolatile memory such as a semiconductor, and stores a system program corresponding to the ultrasonic diagnostic apparatus 100, various processing programs executable on the system program, various data such as a gamma table, and the like. These programs are stored in the form of computer-readable program codes, and the CPU sequentially executes operations according to the program codes. The RAM forms a work area that temporarily stores various programs executed by the CPU and data related to these programs.

A part or all of the functions of each functional block of each unit included in the ultrasonic diagnostic apparatus 100 can be realized as a hardware circuit such as an integrated circuit. An integrated circuit is, for example, an LSI (Large Scale Integration), and LSIs are also called ICs (Integrated Circuits), system LSIs, super LSIs, and ultra LSIs depending on the degree of integration. In addition, the method of integration is not limited to LSI, and it may be realized by a dedicated circuit or a general-purpose processor, and it is possible to reconfigure the connection and setting of circuit cells inside FPGA (Field Programmable Gate Array) and LSI. A reconfigurable processor may be used. Also, a part or all of the functions of each functional block may be executed by software. In this case, this software is stored in one or more storage media such as ROMs, optical discs, hard disks, etc., and this software is executed by the arithmetic processor.

Next, the internal configuration of the ultrasonic probe 2 will be described with reference to FIGS. 3 and 4. FIG. FIG. 3 is a cross-sectional view of the ultrasonic probe 2. As shown in FIG. FIG. 4(a) is a sectional view showing a part of the ultrasonic probe 2 before deformation. FIG. 4(b) is a sectional view showing a part of the ultrasonic probe 2 after deformation.

As shown in FIG. 3, the ultrasonic probe 2 includes a back layer 21, an I/O (Input/Output) electrode 22 as a first electrode, a piezoelectric element 23, and a GND as a second electrode. (GrouND) electrode 24 , acoustic matching layer 25 , acoustic lens 26 , I/O signal line 27 as an electrical signal line, GND signal line 28 as a ground signal line, and thermal deformation portion 29 . . The back layer 21, the I/O electrode 22, the piezoelectric element 23, the GND electrode 24, the acoustic matching layer 25, and the acoustic lens 26 are laminated in this order from the bottom to the top in the front view.

The back layer 21 is made of, for example, a back load material (backing material). The back load material is made of a material whose acoustic impedance is lower than that of the piezoelectric element 23, and is an ultrasonic absorber capable of absorbing unnecessary ultrasonic waves. That is, the backing material absorbs ultrasonic waves generated from the opposite side of the piezoelectric element.

As a back load material, natural rubber, ferrite rubber, epoxy resin, rubber-based composite material, epoxy resin composite material, vinyl chloride, polyvinyl chloride, etc., which are press-molded by adding powder such as tungsten oxide, titanium oxide, and ferrite to these materials. Butyral (PVB), ABS resin, polyurethane (PUR), polyvinyl alcohol (PVAL), polyethylene (PE), polypropylene (PP), polyacetal (POM), polyethylene terephthalate (PETP), fluorine resin (PTFE) polyethylene glycol, polyethylene terephthalate - A thermoplastic resin such as a polyethylene glycol copolymer can be applied.

A preferable back load material is made of a rubber-based composite material and/or an epoxy resin composite material, and its shape is appropriately selected according to the shape of the back layer 21, the piezoelectric element 23, and the probe head including these. can do.

The piezoelectric element 23 has an I/O electrode 22 formed on its lower surface and a GND electrode 24 formed on its upper surface, and is stacked on the back layer 21 . The piezoelectric element 23 is an element (piezoelectric element) having a piezoelectric material, capable of converting electrical signals into mechanical vibrations and mechanical vibrations into electrical signals, capable of transmitting and receiving ultrasonic waves, and having a pyroelectric effect. be.

A piezoelectric material is a material containing a piezoelectric body capable of converting electrical signals into mechanical vibrations and mechanical vibrations into electrical signals. Piezoelectric bodies include lead zirconate titanate (PZT) ceramics, piezoelectric ceramics such as lead titanate and lead metaniobate, lithium niobate, lead zinc niobate and lead titanate, lead magnesium niobate and lead titanate, and the like. Piezoelectric single crystal, crystal, Rochelle salt, polyvinylidene fluoride (PVDF), or polyvinylidene fluoride-ethylene trifluoride, which is a copolymer of VDF and ethylene trifluoride (TrFE), for example PVDF copolymer such as (P (VDF-TrFE)), polyvinylidene cyanide (PVDCN) which is a polymer of vinylidene cyanide (VDCN), or vinylidene cyanide copolymer or nylon 9, nylon 11, etc. Odd number nylon, aromatic nylon, alicyclic nylon, polylactic acid, polyhydroxycarboxylic acid such as polyhydroxybutyrate, cellulose derivative, organic polymer piezoelectric material such as polyurea, and the like can be used.

The thickness of the piezoelectric material is, for example, in the range of 100-500 [μm]. The piezoelectric element 23 is used as the vibrator 2a with the I/O electrodes 22 and the GND electrodes 24 attached to both surfaces thereof.

Materials used for the I/O electrodes 22 and the GND electrodes 24 include gold (Au), platinum (Pt), silver (Ag), palladium (Pd), copper (Cu), aluminum (Al), and nickel (Ni). , tin (Sn), and the like.

As a method of attaching the I/O electrode 22 and the GND electrode 24 to the piezoelectric element 23, for example, an underlying metal such as titanium (Ti) or chromium (Cr) is sputtered to a thickness of 0.02 to 1.0 [μm]. After the above-mentioned metal element is formed as a main component, a metal material composed of a metal or an alloy thereof, and if necessary, a part of an insulating material is formed by sputtering or other appropriate methods to a thickness of 1 to 10 [μm]. A method of forming the thickness is mentioned.

The I/O electrodes 22 and the GND electrodes 24 may be formed by screen printing, dipping, or thermal spraying using a conductive paste obtained by mixing fine metal powder and low-melting-point glass, instead of the sputtering method. The I/O electrodes 22 and the GND electrodes 24 are provided on the surface of the piezoelectric element 23 in accordance with the shape of the ultrasonic probe 2 .

In the piezoelectric element 23, the I/O electrode 22 is electrically connected to the I/O signal line 27, the I/O signal line 27 is electrically connected to the I/O signal line of the cable 3, The GND electrode 24 is electrically connected to the GND signal line 28 , and the GND signal line 28 is electrically connected to the GND signal line of the cable 3 . Therefore, the driving signal output from the ultrasonic diagnostic apparatus main body 1 is input to the piezoelectric element 23 , and the reception signal generated by the piezoelectric element 23 is output to the ultrasonic diagnostic apparatus main body 1 .

The acoustic matching layer 25 matches the acoustic impedance between the piezoelectric element 23 and the acoustic lens 26 and suppresses reflection at each interface between the piezoelectric element 23 , the acoustic matching layer 25 and the acoustic lens 26 . The acoustic matching layer 25 is attached to the subject side with respect to the piezoelectric element 23 .

The acoustic matching layer 25 is composed of a single layer or laminated layers. The acoustic impedance of the acoustic matching layer 25 , which is the combined thickness of a plurality of layers, is set so that it gradually decreases from the bottom layer to the top layer, and the acoustic impedance of the bottom layer is less than the acoustic impedance of the piezoelectric element 23 . Also, in order to match the acoustic impedance of the acoustic lens 26, which will be described later, it is preferable to reduce the difference between the acoustic impedance of the top layer and the acoustic impedance of the acoustic lens 26. More preferably, the difference between the acoustic impedance of the top layer and the acoustic lens 26 is reduced. The acoustic matching layer 25 is provided so that the acoustic impedance of the uppermost layer at the interface is approximately equal to the acoustic impedance of the acoustic lens 26 .

Specific examples of materials used for the acoustic matching layer 25 include aluminum, aluminum alloys (eg, AL-Mg alloy), magnesium alloys, Macor glass, glass, fused silica, copper graphite, PE (polyethylene), and PP (polypropylene). , PC (polycarbonate), ABC resin, ABS resin, AAS resin, AES resin, nylon (PA6, PA6-6), PPO (polyphenylene oxide), PPS (polyphenylene sulfide: glass fiber-containing is also possible), PPE (polyphenylene ether) , PEEK (polyetheretherketone), PAI (polyamideimide), PETP (polyethylene terephthalate), epoxy resin, urethane resin, and the like. Preferably, a thermosetting resin such as an epoxy resin is molded by adding tungsten, zinc oxide, titanium oxide, silica, alumina, red iron oxide, ferrite, tungsten oxide, yttrium oxide, barium sulfate, molybdenum, etc. as a filler. Applicable. Here, by varying the type, amount, distribution, etc. of the filler in each layer, it is possible to make the acoustic impedance of each layer different even if the same type of resin is used.

Acoustic lens 26 is arranged to focus the ultrasonic beam using refraction to improve resolution. That is, the acoustic lens 26 is provided on the side of the ultrasonic probe 2 that contacts the subject, and allows the ultrasonic waves generated by the piezoelectric element 23 to enter the subject efficiently. The acoustic lens 26 has a convex or concave lens shape depending on the speed of sound inside the subject at the part that contacts the subject, and the ultrasonic waves incident on the subject are directed in the thickness direction (elevation direction).

The acoustic impedance of the acoustic lens 26 is appropriately set with respect to the acoustic impedance of the subject so that attenuation and reflection of ultrasonic waves between the acoustic lens 26 and the subject are smaller. Here, since the subject is a human body or the like, the acoustic impedance of the acoustic lens 26 is generally set to be extremely low compared to a hard substance such as a piezoelectric body. For this reason, the acoustic lens 26 is formed of a material (for example, a soft polymer material or the like) corresponding to the set acoustic impedance. In order to further reduce the attenuation and reflection of ultrasonic waves between the acoustic lens 26 and the acoustic matching layer 25, the acoustic impedance of the portion of the acoustic matching layer 25 that contacts the acoustic lens 26 is equal to that of the acoustic lens 26. Preferably they are substantially identical.

Materials for the acoustic lens 26 include homopolymers such as conventionally known silicone-based rubber, butadiene-based rubber, polyurethane rubber, and epichlorohydrin rubber, and ethylene-propylene copolymer rubber obtained by copolymerizing ethylene and propylene. Copolymer rubber and the like are applicable. Among these, silicone-based rubber and butadiene-based rubber are preferably used.

The I/O signal line 27 is made of a conductor and is electrically connected to the I/O electrode 22 of the piezoelectric element 23 with a conductive adhesive or the like. A drive signal from the apparatus main body 1 is transmitted to the I/O electrode 22, and a received signal output from the piezoelectric element 23 that receives the ultrasonic wave from the subject is transmitted to the I/O electrode 22 via the I/O signal line of the cable 3. It is transmitted from the O electrode 22 to the ultrasonic diagnostic apparatus main body 1 . The GND signal line 28 is made of a conductor, is electrically connected to the GND electrode 24 of the piezoelectric element 23 with a conductive adhesive or the like, and is connected to the ground of the ultrasonic diagnostic apparatus main body 1 via the GND signal line of the cable 3. It is The I/O signal line 27, the GND signal line 28, and the thermal deformation portion 29 are arranged in parallel with a gap therebetween.

The thermally deformable portion 29 has a fixed upper end and a released lower end, and has a function of being deformed by temperature. The thermally deformable portion 29 is made of a bimetal made of, for example, zinc, copper, nickel, manganese, ferrite, chromium, molybdenum, zirconium, or aluminum. Here, a bimetal is a material obtained by bonding two or more materials having different coefficients of thermal expansion. In this embodiment, the thermal deformation portion 29 has an inner portion 29a on the side of the piezoelectric element 23 and an outer portion 29b on the outer side of the piezoelectric element 23, and the inner portion 29a and the outer portion 29b are joined. do.

In this embodiment, a material having a low coefficient of thermal expansion is used for the inner portion 29a, and a material having a higher coefficient of thermal expansion than the inner portion 29a is used for the outer portion 29b. For example, the inner portion 29a and the outer portion 29b are formed by joining nickel ferrite alloy and copper, joining chromium ferrite alloy and nickel-chromium ferrite, or joining nickel ferrite alloy and nickel manganese ferrite alloy. There are things. All of the above are a combination of a low thermal expansion material and a high thermal expansion material.

Here, with reference to FIG. 4, the deformation of the thermal deformation portion 29 and its conditions will be described. 4(a) and 4(b) show the piezoelectric element 23, the I/O electrode 22, the GND electrode 24, and the I/O signal line 27 of the ultrasonic probe 2 for the sake of clarity. , and a cross-sectional view showing only the GND signal line 28 and the thermally deformed portion 29. FIG.

When the piezoelectric element is exposed to a high temperature, an electric field is generated by the pyroelectric effect, and the electric field depolarizes the piezoelectric element, degrading its characteristics. However, in the ultrasonic probe 2 of the present embodiment, as shown in FIG. 4A, the I/O signal line 27, the GND signal line 28, and the thermally deformed portion 29 form a gap at normal temperature. As the temperature of the ultrasonic probe 2 rises, the thermal deformation portion 29 deforms toward the GND signal line 28 side. Furthermore, as shown in FIG. 4(b), the thermally deformed portion 29 causes the GND signal line 28 and the I/O signal line 27 to come into contact with each other due to the temperature rise, thereby electrically short-circuiting them.

In other words, it is possible to suppress the generation of an electric field caused by the pyroelectric effect of the piezoelectric element that occurs at high temperatures, thereby eliminating deterioration in the characteristics of the piezoelectric element 23 . That is, deterioration of the characteristics of the ultrasonic probe 2 can be eliminated. Although the thermal deformation portion 29 is arranged on the GND signal line 28 side in the present embodiment, the thermal deformation portion may be arranged on the I/O signal line 27 side. Alternatively, the thermally deformed portion may be arranged on both the GND signal line 28 side and the I/O signal line 27 side.

Note that the thermally deformed portion 29 deforms as the temperature rises, but this deformation is ten times or more the deformation due to the thermal expansion of the I/O signal line 27 and the GND signal line 28 themselves. For example, when the I/O signal line 27 and the GND signal line 28 are made of a metal conductor and each dimension is 0.1 [mm], deformation due to thermal expansion of the I/O signal line 27 and the GND signal line 28 themselves is about 0.1 [μm], but the gap between the I/O signal line 27 and the GND signal line 28 is set to 1 [μm] or more in consideration of dimensional variations. Deformation due to thermal expansion of the wire 28 itself cannot bring the GND signal wire 28 and the I/O signal wire 27 into contact and electrically short-circuit as the temperature of the ultrasonic probe rises.

In conventional ultrasonic probes, an abnormality occurs in the polarization of the piezoelectric element due to the pyroelectric effect of the piezoelectric element as the temperature rises. Abnormalities occur in the resonance characteristics of the piezoelectric element, causing unwanted resonance. However, in the ultrasonic probe 2 of the present embodiment, the polarization of the piezoelectric element does not become abnormal even at high temperatures, and unnecessary resonance does not occur.

When the thermally deformed portion 29 is a bimetal, as shown in FIGS. 4A and 4B, the distance A between the I/O signal line 27 and the thermally deformed portion 29, and the thickness The thickness B, the thickness t of the thermally deformed portion 29, the length L of the thermally deformed portion 29 in the vertical direction in the drawing, and the amount of curvature D of the thermally deformed portion 29 are taken. Assuming that the curvature coefficient is K and the temperature range is ΔT, the amount of curvature D is expressed by the following equation (1) using the thickness t and the length L of the thermally deformed portion 29 .
D=K×ΔT×L×L÷t (1)

Generally, the upper limit of the operating temperature of the ultrasonic probe is 70 [°C]. That is, since the ultrasonic probe is not used at 70[°C] or higher, it is desirable to short-circuit the I/O signal line 27 and the GND signal line 28 at 70[°C] or higher. An example of short-circuiting the I/O signal line 27 and the GND signal line 28 at 70[° C.] or higher is as follows.
K = 15 × 10 ^-6 (for example, BL-2 (manufactured by Hitachi Metals Neomaterial) is used as the thermal deformation portion 29),
ΔT = 50°C (room temperature: 20 [°C], high temperature: 70 [°C]),
L=10 [mm],
Let t=0.05 [mm].

Here, let distance C be the difference between distance A and the distance between the I/O signal line 27 and the GND signal line 28 . From the equation (1), the amount of curvature D is 1.5 [mm]. By short-circuiting with the line 28, the electric field generated by the pyroelectric effect can be eliminated and the characteristic deterioration can be suppressed. Therefore, the GND signal line 28 and the I/O signal line 27 can be brought into contact and electrically short-circuited with the same amount of deformation no matter where the thermal deformation portion 29 is provided.

As described above, according to the present embodiment, the ultrasonic probe 2 is electrically connected to the piezoelectric element 23 that transmits and receives ultrasonic waves to and from the subject, and the I/O electrode 22 provided on the piezoelectric element 23, An I/O signal line 27 through which a drive signal input to the piezoelectric element 23 and a reception signal output from the piezoelectric element 23 flow, and a GND provided on the piezoelectric element 23 with a gap between the I/O signal line 27 and the I/O signal line 27. The GND signal line 28 electrically connected to the electrode 24 is deformed due to the temperature rise, and the heat that contacts the I/O signal line 27 and the GND signal line 28 at a predetermined temperature (high temperature: for example, 70 [° C.]) or higher. and a deformation portion 29 .

For this reason, it is possible to suppress the generation of an electric field caused by the pyroelectric effect of the piezoelectric element that occurs at high temperatures, and the electrical control for preventing the pyroelectric effect and its cost are unnecessary, so that the deterioration of the characteristics of the piezoelectric element 23 due to the pyroelectric effect can be suppressed. can be easily eliminated, and deterioration of the characteristics of the ultrasonic probe 2 can be eliminated.

Moreover, the thermal deformation portion 29 is made of bimetal. Therefore, it is possible to suppress the generation of an electric field caused by the pyroelectric effect at a temperature equal to or higher than a predetermined temperature.

Also, the I/O signal line 27, the GND signal line 28, and the thermal deformation portion 29 are arranged in parallel. Therefore, the GND signal line 28 and the I/O signal line 27 can be brought into contact and electrically short-circuited with the same amount of deformation no matter where the thermal deformation portion 29 is provided.

The ultrasonic diagnostic apparatus 100 also includes an ultrasonic probe 2, a transmission unit 12 that generates a driving signal and outputs it to the ultrasonic probe 2, and a received signal input from the ultrasonic probe 2. and an image generation unit 14 that generates ultrasound image data based on. Therefore, deterioration of the characteristics of the piezoelectric element 23 and the deterioration of the characteristics of the ultrasonic probe 2 due to the pyroelectric effect can be eliminated, and ultrasonic image data without deterioration can be generated.

(First embodiment)
A first example of the above embodiment will be described with reference to FIG. FIG. 5(a) is a sectional view showing a part of the ultrasonic probe 2A before deformation. FIG. 5(b) is a sectional view showing a part of the ultrasonic probe 2A after deformation.

The apparatus configuration of this embodiment uses an ultrasonic diagnostic apparatus 100 in which the ultrasonic probe 2 of the above embodiment is replaced with an ultrasonic probe 2A of this embodiment. For this reason, the same reference numerals are given to the same components as in the above-described embodiment, and the description thereof will be omitted.

As shown in FIG. 5A, the ultrasonic probe 2A includes a back layer 21, an I/O electrode 22A, a piezoelectric element 23, a GND electrode 24A, an acoustic matching layer 25, and an acoustic lens 26. , an I/O signal line 27A, a GND signal line 28A, a cavity portion 30, an insulator portion 31, a cavity portion 32, and a thermal deformation portion 29. The back layer 21, the I/O electrode 22A, the piezoelectric element 23, the GND electrode 24A, the acoustic matching layer 25, and the acoustic lens 26 are laminated in this order from the bottom to the top in the front view. However, FIGS. 5A and 5B show the piezoelectric element 23, I/O electrode 22A, GND electrode 24A, and I/O signal line 27A of the ultrasonic probe 2A for easy understanding. , GND signal line 28A, hollow portion 30, insulator portion 31, hollow portion 32, and thermal deformation portion 29 only.

The I/O electrode 22A is an I/O electrode formed on the bottom surface of the piezoelectric element 23 . The GND electrode 24A is a GND electrode formed on the upper surface, side surfaces, and part of the lower surface of the piezoelectric element 23 . The I/O electrode 22A and the GND electrode 24A are electrically insulated by the cavity 30. As shown in FIG.

The I/O signal line 27A is made of a conductor and electrically connected to the I/O electrode 22A. The GND signal line 28A is made of a conductor and electrically connected to the GND electrode 24A. The insulator portion 31 is made of an insulator. The I/O signal line 27A is formed on both surfaces of the insulator portion 31, and the GND signal line 28A is formed on one surface of the insulator portion 31. As shown in FIG. In this manner, the insulator portion 31, the I/O signal line 27A, and the GND signal line 28A are laminated. The I/O signal line 27A and the GND signal line 28A are insulated by the hollow portion 30 and the insulator portion 31 . The insulator portion 31 may be, for example, a base portion of a flexible substrate (FPC: Flexible Printed Circuit) made of an insulator film such as polyimide. In this configuration, the I/O signal line 27A, insulator portion 31, and GND signal line 28A function as a flexible substrate.

The hollow portion 32 is a gap between the insulator portions 31 and is arranged at a position where the thermally deformed portion 29 short-circuits the GND signal line 28A and the I/O signal line 27A. Since the insulator portion 31 is provided around the hollow portion 32, the I/O signal line 27A and the GND signal line 28A are not short-circuited except at high temperatures. As shown in FIG. 5B, the I/O signal line 27A and the GND signal line 28A become hollow due to the deformation of the thermally deformed portion 29 at a high temperature (e.g., 70 [° C.] or higher). The electrical contacts at portion 32 are short-circuited.

As described above, according to the present embodiment, the ultrasonic probe 2A includes the insulator portion 31 on the surface of which the I/O signal line 27A and the GND signal line 28A are formed, and the I/O signal line 27A and the GND signal line. 28A, and the deformation of the thermal deformation portion 29 causes the I/O signal line 27A and the GND signal line 28A to come into contact with each other. Therefore, deterioration of the characteristics of the piezoelectric element 23 and the deterioration of the characteristics of the ultrasonic probe 2 due to the pyroelectric effect can be eliminated, and the insulation between the I/O signal line 27A and the GND signal line 28A can be improved.

(Second embodiment)
A second example of the above embodiment will be described with reference to FIG. FIG. 6(a) is a sectional view showing a part of the ultrasonic probe 2B before deformation. FIG. 6(b) is a sectional view showing a part of the ultrasonic probe 2B after deformation.

The apparatus configuration of this embodiment uses an ultrasonic diagnostic apparatus 100 in which the ultrasonic probe 2 of the above embodiment is replaced with the ultrasonic probe 2B of this embodiment. For this reason, the same reference numerals are given to the same components as in the above-described embodiment, and the description thereof will be omitted.

As shown in FIG. 6A, the ultrasonic probe 2B includes a back layer 21, an I/O electrode 22, a piezoelectric element 23, a GND electrode 24, an acoustic matching layer 25, and an acoustic lens 26. , an I/O signal line 27 , a GND signal line 28 B, and a thermal deformation portion 29 . 6(a) and 6(b) show the piezoelectric element 23, the I/O electrode 22, the GND electrode 24, and the I/O signal line 27 of the ultrasonic probe 2B for the sake of clarity. , and a cross-sectional view showing only the GND signal line 28B and the thermally deformed portion 29. FIG.

The GND signal line 28B is made of a conductor and electrically connected to the GND electrode 24A. The thermally deformable portion 29 is made of a conductor, has a function of deforming due to temperature, and functions as a part of the GND signal line 28B.

As shown in FIG. 6(b), as the temperature of the ultrasonic probe 2B rises, the thermal deformation portion 29 deforms toward the I/O signal line 27, and the temperature further rises (predetermined temperature (for example, 70 [ °C]) above), the I/O signal line 27 is contacted, and the I/O signal line 27 and the GND signal line 28B are electrically short-circuited. In other words, it is possible to suppress the generation of an electric field caused by the pyroelectric effect of the piezoelectric element 23 that occurs at high temperatures, thereby eliminating deterioration in the characteristics of the piezoelectric element 23 . That is, it is possible to eliminate deterioration of the characteristics of the ultrasonic probe 2B.

As described above, according to this embodiment, the thermal deformation portion 29 is made of a conductor and functions as a part of the GND signal line 28A. Therefore, it is possible to eliminate deterioration of the characteristics of the piezoelectric element 23 and the deterioration of the characteristics of the ultrasonic probe 2B due to the pyroelectric effect. can be made smaller.

In this embodiment, the thermally deformable portion 29 is arranged as part of the GND signal line 28B, but may be arranged as part of the I/O signal line. In this configuration, the thermal deformation portion 29 is in contact with the GND signal line at high temperatures. Similarly, the ultrasonic probe may have a thermally deformed portion that functions as part of the GND signal line and a thermally deformed portion that functions as part of the I/O signal line.

(Third embodiment)
A third example of the above embodiment will be described with reference to FIG. FIG. 7(a) is a sectional view showing a part of the ultrasonic probe 2C before deformation. FIG. 7(b) is a sectional view showing a part of the ultrasonic probe 2C after deformation.

The apparatus configuration of this embodiment uses an ultrasonic diagnostic apparatus 100 in which the ultrasonic probe 2 of the above embodiment is replaced with an ultrasonic probe 2C of this embodiment. For this reason, the same reference numerals are given to the same components as in the above-described embodiment, and the description thereof will be omitted.

As shown in FIG. 7A, the ultrasonic probe 2C includes a back layer 21, an I/O electrode 22, a piezoelectric element 23, a GND electrode 24, an acoustic matching layer 25, and an acoustic lens 26. , an I/O signal line 27 , a GND signal line 28</b>C, a thermal deformation portion 29 , and an insulator portion 33 . However, FIGS. 7A and 7B show the piezoelectric element 23, the I/O electrode 22, the GND electrode 24, and the I/O signal line 27 of the ultrasonic probe 2C for easy understanding. , and a GND signal line 28C, a thermal deformation portion 29, and an insulator portion 33 only.

The GND signal line 28C is made of a conductor and electrically connected to the GND electrode 24A. The thermally deformable portion 29 is made of a conductor, has a function of deforming due to temperature, and functions as a part of the GND signal line 28C.

The insulator portion 33 is, for example, a base portion of a flexible substrate made of an insulator film such as polyimide. The GND signal line 28C and the thermal deformation portion 29 are formed on the surface of the insulator portion 33 on the piezoelectric element 23 side. In this manner, the GND signal line 28A or the thermal deformation portion 29 and the insulator portion 33 are laminated in order from the piezoelectric element 23 side to the outside. The insulator portion 33 easily holds the thermally deformed portion 29 and provides electrical insulation from the outside to the piezoelectric element 23, I/O electrode 22, GND electrode 24, I/O signal line 27, and GND signal line 28C. It is possible.

As the temperature of the ultrasonic probe 2C rises, the thermally deformable portion 29 deforms toward the I/O signal line 27, and the temperature rise (e.g., 70 [° C.] or higher) causes the I/O It comes into contact with the signal line 27 and electrically short-circuits the I/O signal line 27 and the GND signal line 28C. In other words, it is possible to suppress the generation of an electric field caused by the pyroelectric effect of the piezoelectric element 23 that occurs at high temperatures, thereby eliminating deterioration in the characteristics of the piezoelectric element 23 . That is, it is possible to eliminate deterioration of the characteristics of the ultrasonic probe 2C.

As described above, according to the present embodiment, the ultrasonic probe 2C is arranged outside the I/O signal line 27 and the GND signal line 28C, and the GND signal line 28C is formed on the surface on the piezoelectric element 23 side (inner side). An insulator portion 33 is provided. Therefore, deterioration of the characteristics of the piezoelectric element 23 and the deterioration of the characteristics of the ultrasonic probe 2C due to the pyroelectric effect can be eliminated, and the piezoelectric element 23, the I/O electrode 22, the GND electrode 24, and the I/O signal can be supplied from the outside. Line 27 allows electrical isolation to the GND signal line 28C.

In this embodiment, the thermally deformable portion 29 is arranged on the GND signal line 28C side so as to be a part of the GND signal line 28C (contacting the I/O signal line 27 at high temperatures). It may be arranged on the signal line 27 side and used as a part of the I/O signal line 27 (in contact with the GND signal line 28C at high temperatures). Alternatively, the ultrasonic probe is arranged on the GND signal line side and is part of the GND signal line, and the thermal deformation part is arranged on the I / O signal line side and is part of the I / O signal line. It is good also as a structure provided with a part.

(Fourth embodiment)
A fourth example of the above embodiment will be described with reference to FIG. FIG. 8(a) is a cross-sectional view showing a part of the ultrasonic probe 2D before thermal deformation. FIG. 8(b) is a sectional view showing a part of the ultrasonic probe 2D after thermal deformation.

The apparatus configuration of this embodiment uses an ultrasonic diagnostic apparatus 100 in which the ultrasonic probe 2 of the above embodiment is replaced with the ultrasonic probe 2D of this embodiment. For this reason, the same reference numerals are given to the same components as in the above-described embodiment, and the description thereof will be omitted.

As shown in FIG. 8A, the ultrasonic probe 2D includes a back layer 21, an I/O electrode 22, a piezoelectric element 23, a GND electrode 24, an acoustic matching layer 25, and an acoustic lens 26. , an I/O signal line 27, a GND signal line 28, and a thermal deformation portion 29D. However, FIGS. 8A and 8B show the piezoelectric element 23, the I/O electrode 22, the GND electrode 24, and the I/O signal line 27 of the ultrasonic probe 2D for easy understanding. , a GND signal line 28, and a thermally deformed portion 29D only.

The thermally deformable portion 29D has a fixed upper end and a released lower end, and has a function of deforming due to temperature and a heat dissipation function. When the piezoelectric element 23 transmits ultrasonic waves, heat is generated due to electroacoustic conversion loss. In order to reduce this heat generation, a heat radiating member made of a material such as metal having high thermal conductivity is required around the piezoelectric element 23 . Materials with high thermal conductivity include metals, and among metals, copper, molybdenum, and aluminum are preferred. For this reason, the thermally deformable portion 29D is made of, for example, a bimetal containing the above metal as a heat dissipation member.

Moreover, the thermally deformable portion 29D has a larger surface area than the thermally deformable portion 29 of the above-described embodiment, thereby improving the heat radiation effect. The thermally deformable portion 29D suppresses the heat generation of the piezoelectric element 23 by its heat radiation function, suppresses the generation of an electric field caused by the pyroelectric effect of the piezoelectric element 23 at high temperatures, and eliminates deterioration of the characteristics of the piezoelectric element 23. In other words, it is possible to eliminate deterioration of the characteristics of the ultrasonic probe 2D, and reduce the heat generated when the piezoelectric element 23 transmits ultrasonic waves.

As described above, according to the present embodiment, the thermally deformable portion 29D is made of a material such as a metal having high thermal conductivity and has a large planar area, so it has a heat dissipation function. Therefore, the deterioration of the characteristics of the piezoelectric element 23 and the deterioration of the characteristics of the ultrasonic probe 2D due to the pyroelectric effect can be eliminated, and the heat generated when the piezoelectric element 23 transmits ultrasonic waves can be reduced. .

It should be noted that the descriptions in the above embodiments and examples are examples of a suitable ultrasonic probe and ultrasonic diagnostic apparatus according to the present invention, and the present invention is not limited to these. For example, at least two of the above embodiments and examples may be combined as appropriate.

In addition, the detailed configuration and detailed operation of each part constituting the ultrasonic diagnostic apparatus 100 in the above embodiments and examples can be changed as appropriate without departing from the scope of the present invention.

100 Ultrasound diagnostic apparatus 1 Ultrasound diagnostic apparatus main body 11 Operation input unit 12 Transmission unit 13 Reception unit 14 Image generation unit 15 Image processing unit 15a Image memory unit 16 DSC
17 display unit 18 control unit 2, 2A, 2B, 2C, 2D ultrasonic probe 21 back layer 22, 22A I/O electrode 23 piezoelectric element 24, 24A GND electrode 25 acoustic matching layer 26 acoustic lens 27, 27A I/ O signal lines 28, 28A, 28B, 28C GND signal lines 29, 29D Thermal deformation parts 30, 32 Cavity parts 31, 33 Insulator part 2a Vibrator 3 Cable

Claims (9)

a piezoelectric element that transmits and receives ultrasonic waves to and from a subject;
an electric signal line electrically connected to a first electrode provided on the piezoelectric element, through which a drive signal input to the piezoelectric element and a reception signal output from the piezoelectric element flow;
a ground signal line provided with a gap from the electric signal line and electrically connected to a second electrode provided on the piezoelectric element;
and a thermally deformable portion that deforms due to temperature and brings the electrical signal line and the ground signal line into contact at a predetermined temperature or higher. 2. The ultrasonic probe according to claim 1, wherein the thermally deformable portion is made of a conductor and functions as part of at least one of the electrical signal line and the ground signal line. 3. The ultrasonic probe according to claim 1, wherein at least one of said electric signal line and said ground signal line has an insulator portion formed on a surface thereof. The electrical signal line and the ground signal line are formed on the surface of the insulator,
4. The ultrasonic probe according to claim 3, further comprising: a cavity that insulates the electric signal line and the ground signal line, and contacts the electric signal line and the ground signal line due to deformation of the thermally deformable portion. . 4. The ultrasonic wave according to claim 3, wherein the insulator part is arranged outside the electric signal line and the ground signal line, and the electric signal line or the ground signal line is formed on the surface on the piezoelectric element side. probe. The ultrasonic probe according to any one of claims 1 to 5, wherein the thermally deformable portion is made of bimetal. The ultrasonic probe according to any one of claims 1 to 6, wherein the thermally deformable portion has a heat radiation function. The ultrasonic probe according to any one of claims 1 to 7, wherein the electric signal line, the ground signal line, and the thermal deformation portion are arranged in parallel. The ultrasonic probe according to any one of claims 1 to 8,
a transmission unit that generates the drive signal and outputs it to the ultrasonic probe;
An ultrasonic diagnostic apparatus comprising: an image generation unit that generates ultrasonic image data based on the received signal input from the ultrasonic probe.

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